The hypotheses for this study are based on the results of a substudy of a large, longitudinal epidemiologic investigation (CARDIA), which demonstrated that 24-hr cGMP excretion was higher in African-Americans than whites; higher in men than women; higher in smokers than non- smokers; and higher in persons with a positive family history of hypertension than persons with a negative family history of hypertension. We propose to maintain 20 women (10 pre- and 10 post- menopausal) on two days of low nitrate/nitrite diet and then correlate 24-hr urinary cGMP excretion with resting BP and BP responses to stress. We anticipate that this preliminary study will lead to multiple, larger testings.